Coronary Collaterals Function and Clinical Outcome Between Patients With Acute and Chronic Total Occlusion

This study sought to demonstrate how changes in the collateral function and its clinical significance before and after percutaneous coronary interventions (PCIs) are compared between patients with acute coronary syndrome and total or nearly total occlusions (ATOs) and chronic total occlusions (CTOs).

The functional relevance of the collateral circulation in patients with ATOs and CTOs has not been fully investigated.

The pressure-derived collateral pressure index (CPI), myocardial fractional flow reserve (FFRmyo), and coronary fractional flow reserve (FFRcor) at maximum hyperemia induced by intravenous adenosine were evaluated in occluded vessels at baseline, after the PCI, and at 1 year in 23 ATO and 74 CTO patients.

The FFRmyo and FFRcor were significantly lower, but the CPI was significantly higher in the CTO than ATO patients at baseline and after the PCI. There were significant increases in the FFRmyo (p < 0.001) and FFRcor (p < 0.001), whereas there was no significant change in the CPI immediately after the PCI in both ATO and CTO patients. In the CTO patients, a post-PCI FFRmyo <0.90 (p = 0.01) and post-PCI CPI <0.25 (p = 0.033) were independent predictors of the clinical outcome. Patients with a high post-PCI CPI had better clinical outcomes in CTO patients with a low post-PCI FFRmyo (log-rank p = 0.009), but not a high post-PCI FFRmyo (log-rank p = 0.492).

Recruitable coronary collateral flow did not regress completely immediately after the PCI both in patients with ATOs and CTOs. Despite good collaterals in CTO patients, aggressive efforts to reduce the ischemic burden might improve the clinical outcome.